Looks like Baclofen is a muscle relaxant. That would explain why it's not broadly used.
What should I avoid while taking baclofen?
Do not use baclofen at a time when you need muscle tone for safe balance and movement during certain activities. In some situations, it may be dangerous for you to have reduced muscle tone.
Drinking alcohol with this medicine can cause side effects.
This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.